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Gonzalo forecast to become a hurricane, Tropical Depression Eight in the Gulf is getting organized

July 23, 2020 satellite image of the tropics.
July 23, 2020 satellite image of the tropics. (CIRA/RAMMB)

There are two systems to watch in the tropics, and both are forecast to affect land areas this weekend. Gonzalo will move through the eastern Caribbean islands – Hurricane Watches are in effect. And Tropical Depression Eight in the Gulf of Mexico is forecast to cross the Texas coast, possibly as Tropical Storm Hanna.

As the Tropical Depression in the Gulf is slowly organizing, it continues to pull its moisture tail over South Florida. This unusually moist air will cause general cloudiness with some bands of tropical downpours to continue, at least for today. 

The water in the Gulf is plenty warm, and the upper winds are conducive for development. If thunderstorms continue to organize around the center of circulation, the system could quickly spin up into Tropical Storm Hanna. It’s not forecast to reach the Texas coast until Saturday, which gives it plenty of time to organize. 

Tropical Depression Eight, July 23 7 a.m. advisory.
Tropical Depression Eight, July 23 7 a.m. advisory. (www.HurricaneIntel.com)

Heavy rain and flooding will likely occur well away from wherever the center comes ashore, so the exact landfall point is not really important, and unforecastable in a disorganized system like this in any case.

Well out in the Atlantic, just over 1,000 miles east of the Caribbean islands, Tropical Storm Gonzalo is organizing in fits and starts.  It’s a tiny system, so it takes a pristine atmosphere to really rev up. Some dry, dusty air has wrapped into the system which has tried to disrupt the circulation. If Gonzalo can find a moist corridor south of the dust plume, the overall conditions appear conducive for it to strengthen into a hurricane later today or tonight. 

When Gonzalo reaches the Caribbean islands over the weekend, it’s unclear how strong it will be. There are indications that it will be weakening by that time, but that’s not guaranteed. Over the Caribbean Sea, the wind regime is not forecast to be favorable for the system to maintain its strength, but it’s unclear when that weakening process would start. There is also the Saharan Dust lurking nearby.

Tropical Storm Gonzalo, July 23 8 a.m. advisory.
Tropical Storm Gonzalo, July 23 8 a.m. advisory. (www.HurricaneIntel.com)

The National Hurricane Center is forecasting Gonzalo to be a strong tropical storm when it moves through the islands, which is a compromise between the evidence that says it will be a hurricane, and the contrary evidence that says it won’t be much more than a moisture surge.

With the uncertainty intrinsic in forecasting the effects both system will have on land, it’s important to remember that forecast errors are larger in developing or weak systems, which both of these are. Don’t focus on the exact forecast track. Stay aware and stay informed.

Whatever strength Gonzalo is when it goes through the islands, the best evidence is that the system will pass through the Caribbean and stay well south of Florida. 

Long-range computer models show another system eventually moving off of Africa south of the Sahara Dust plume, but nothing else is expected to develop in the Atlantic, Caribbean, or Gulf of Mexico through the weekend into early next week.

In the Pacific, Hurricane Douglas is heading in the general direction of Hawaii. There is relatively cold ocean water between where the storm is now and the Big Island, so it’s expected to weaken, but it could still be a significant storm when it gets there on Sunday. The Hawaiian Islands are very mountainous, and even tropical storms can have significant effects at high elevations.

Hurricane Douglas, July 22 11 p.m. advisory.
Hurricane Douglas, July 22 11 p.m. advisory. (www.HurricaneIntel.com)

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